Effect of copper on the activation of the acid phosphatase from the green algae <Emphasis Type="Italic">Pseudokirchneriella subcapitata</Emphasis>

The presence of copper in water environment may have detrimental effects on aquatic organisms, including algae, where different enzymatic systems can be affected. Algae acid phosphatase plays important roles in metabolic processes such as decomposition of organic phosphate, autophagic digestive process, recycling cellular materials and zygote formation during reproduction. This work describes an in vitro activation effect of copper on the acid phosphatase of the green algae Pseudokirchneriella subcapitata (formely Selenastrum capricornutum) under preincubation condition. Apparent Michaelis constant values of 1.21 and 0.37 mM, and activation energy values of 26.8 and 13.6 kJ mol⁻¹ were determined in the absence and in the presence of 0.2 mM Cu²⁺, respectively. The dissociation constant value for Cu²⁺ binding to the enzyme was determined to be 22.04 μM. The decrease of the apparent Michaelis constant (Km) and activation energy values in the presence of Cu²⁺ correlates well with its activating effect on the acid phosphatase activity. This propriety could be used as a sensitive bioindicator for copper in environmental samples.